I think the file that steam runs when you launch counter-strike is:
~/.local/share/Steam/SteamApps/common/Half-Life/hl.sh
which is a script that then launches the binary.
The actual binary is in the same directory as that script and called "hl_linux"

This is how css gets launched so to launch cs via HL1 shouldn't be too much different_________________the table is made from wood. forget what you learnt, the table is made from carbon. forget what you learnt, the table is made from protons. forget what you learnt, the table is made from quarks. forget what you learnt, the table is good for shagging on